Given the following list of atomic and ionic species, find the appropriate match for questions 2-4. explain.

(a) fe^2+ (b) cl (c) k^+ (d) cs (e) hg^+

2. has a noble gas electron configuration.

3. has electrons in f orbitals.

4. is isoelectronic with gold.

2. (C) K⁺; 3. (E) Hg⁺; 4. Hg⁺

Explanation:

We must first write the electron configurations of the different species.

(A) Fe²⁺

Fe:     [Ar]4s²3d⁶

Fe²⁺: [Ar]3d⁶

When removing electrons from a transition metal ion, you remove the s electrons first.

(B) Cl

Cl: [Ne]3s²3p⁵

(C) K⁺

K:   [Ar]4s

K⁺: [Ar]

(D) Cs

Cs: [Xe]6s

(E) Hg⁺

Hg:   [Xe]6s²4f¹⁴5d¹⁰

Hg⁺: [Xe]6s4f¹⁴5d¹⁰

2. K⁺ has a noble gas configuration

3. Hg⁺ has electrons in f orbitals.

4. The electron configuration of Au is [Xe]6s4f¹⁴5d¹⁰, not [Xe]6s²4f¹⁴5d⁹, because a filled d subshell is more stable than a filled s subshell.

Thus, Hg⁺ is isoelectronic with Au.